Birds have two basic types of sounds : songs and call. Songs are usually more complex than calls and are utilized primarily by adult males during the breeding season to establish territories or attract mates. Calls are normally simple notes, single or repeated, vocalized by males and females in all seasons to express alarm or maintain contact with mates, offspring, or other birds of the same species. All songs and most calls are distinctive, with concentrated study and practice, bird-watchers can learn to identify many birds by their sounds and to calls them well.